Methods and apparatus for diagnosing and remediating reading disorders

ABSTRACT

Reading disorders are diagnosed and remediated in a subject by respectively measuring and improving contrast sensitivity for motion discrimination of the subject. A background is displayed on a monitor with a contrast and a spatial frequency. A test window is superimposed over the background and includes a test pattern with a contrast and a spatial frequency. The contrasts and the spatial frequencies are within respective ranges which stimulate the visual cortical movement system of the subject. The test pattern is then moved within the test window. The subject provides a signal indicative of the direction the subject believes the test pattern moved. In response to this signal, the contrast of the test pattern, the spatial frequency of the background, or the spatial frequency of the test pattern is modified, either by increasing or decreasing its respective value. This process is then repeated a number of times, cycling through predetermined combinations of test patterns and backgrounds. Contrast sensitivity may be measured to determine whether a child is dyslexic. Repeated stimulation by the methods and apparatus of the invention improves contrast sensitivity, thereby remediating dyslexia and improving reading ability.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application Ser. No. 60/041,916 filed Apr. 7, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methodology for diagnosing and treatingreading disorders such as dyslexia. More particularly, the presentinvention relates to methods and apparatus for measuring contrastsensitivity for motion discrimination. The present invention alsorelates to methods and apparatus for improving contrast sensitivity formotion discrimination. The inventor of the present invention hasdetermined that by improving contrast sensitivity for motiondiscrimination by practicing the present invention, children who aredyslexic, as well as children with normal reading ability, may improvetheir reading ability.

2. Description of the Related Art

When a pattern of light falls on the retina, the image is processedwithin the retina to some extent Ganglion cells of the retina sendsignals out of the eye to a relay nucleus in the thalamus of the brain.Cells of the thalamus in turn send signals to the visual cortex forfurther processing. There are two major types of retinal ganglion cellswhich respectively contact two divisions of cells in the relay nucleusof the thalamus: the parvocellular division and the magnocellulardivision. Cells in the parvocellular division have small receptivefields and are useful for visual tasks requiring a high degree ofacuity. Cells in the magnocellular division, which are about ten-timesless numerous than those of the parvocellular division, have largereceptive fields and are useful for visual tasks requiring a high degreeof movement detection. Cells of the magnocellular division have coarseacuity and high contrast sensitivity.

In view of the above, the vision system of a human may be divided intotwo visual streams. The first stream is a magnocellular stream whichdetects the movement of an object. This movement stream has a highsensitivity to low contrast (for example, below 10%), to low luminance,to movement, and has low resolution. The second stream is aparvocellular stream which detects the color, shape, and texture ofpatterns. This second or acuity steam has low contrast sensitivity andhigh resolution. The acuity stream is most sensitive to contrasts aboveabout 10%.

The parvocellular and magnocellular cells, either alone or incombination, provide the information used by many different visualcortical pathways (or "streams") which are specialized at performingdifferent perceptual tasks. One such specialized pathway is a visualcortical area called Medial Temporal, or "MT," which is central in theanalysis of direction of motion. Most of the signals that drive neuronsin area MT derive from neurons in layer 4b of the primary visual cortex,which neurons in turn are primarily supplied by input from themagnocellular cells. (In primates, the primary visual cortex is the onlycortical area that receives signals from the retina via neurons in thethalamic relay nucleus.) Direction selectivity is a fundamentalcharacteristic of the magnocellular neurons and is mediated by cells inboth layer 4b in the striate cortex and in the MT cortex.

Certain aspects of magnocellular networks, such as directiondiscrimination and detecting brief patterns, are still developing in all5 to 9 year old children, when compared to normal adults. Moreover, theimmature magnocellular and inhibitory networks of dyslexics confirm theincreasing psychophysical, physiological, and anatomical evidence thatdyslexics have anomalies in their magnocellular networks, demonstratedby (1) higher contrast thresholds to detect brief patterns, (2) animpaired ability to discriminate both the direction and the velocity ofmoving patterns, and (3) unstable binocular control and depthlocalization when compared to age-matched normals. There is substantialevidence that dyslexics have a disordered posterior parietal cortex andcorpus callosum, having immature inhibitory networks that severely limita child's ability to both discriminate direction of movement and read.

Reading is the most important skill that is learned in the first andsecond grades. Yet there are no standardized ways to evaluate or toteach reading. A natural assumption is that reading relies on the higherresolution pattern system evaluated by measuring an observer's visualacuity and color discrimination ability. It is generally believed thatmovement discrimination is involved in reading solely as a means ofdirecting eye movements, coordinating each saccade so that letterrecognition can be conveyed by the portion of the vision system whichhas a higher resolution. It is intriguing that differences betweenchildren with reading problems (e.g., those who are dyslexic) andchildren with normal reading ability were revealed only by tests of thecortical movement system. On the other hand, tests of the patternsystem, such as visual acuity using long duration patterns, revealed nodifferences between children with normal reading and children withreading problems. However, a recent study questions whether dyslexicchildren show a temporal processing deficit, and another study concludesthat the contrast sensitivity functions (CSFs) of dyslexic children areunrelated to their reading ability.

A natural assumption in the art is that reading relies on thehigh-resolution acuity system. The acuity system may be evaluated bymeasuring the visual acuity of a subject, which is measured by an indexof 20/20, 20/40, and so on as known in the art. Conventional wisdom inthe art teaches that dyslexia, which may be defined as a difficulty inreading in a child of normal intelligence and an adult-level acuity(i.e., 20/20), is explained as a difficulty in decoding words on a pagethat are readily seen.

One approach used to remediate dyslexia involves training the child toengage in novel, small-scale hand-eye coordination tasks like drawing,painting, and modeling, coupled with word identification, for 5 hoursper week over 8 months. This approach improved reading at least onegrade level. The mechanism for this improvement is unknown.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing drawbacks of current techniques in the art, oneof the objectives of the present invention is to provide methods andapparatus for diagnosing and remediating reading disorders byrespectively measuring and improving contrast sensitivity for motiondiscrimination of the subject. Dyslexic children who have practiced themethods of the present invention have increased their reading rates upto 9 times on average. There is also a marked increase in reading ratesin children with previously determined normal ability.

According to one aspect of the invention, a background is displayed on amonitor with a contrast and a spatial frequency. A test window issuperimposed over the background and includes a test pattern with acontrast and a spatial frequency. The contrasts and the spatialfrequencies are within respective ranges which stimulate the visualcortical movement system of the subject. The test pattern is then movedwithin the test window. The subject provides a signal indicative of thedirection the subject believes the test pattern moved. In response tothis signal, the contrast of the test pattern, the spatial frequency ofthe background, or the spatial frequency of the test pattern ismodified, either by increasing or decreasing its respective value.

This process is then repeated a number of times, cycling throughpredetermined combinations of test patterns and backgrounds. Contrastsensitivity may be measured to determine whether a child is dyslexic.Repeated stimulation by the methods and apparatus of the inventionimproves contrast sensitivity, thereby remediating dyslexia andimproving reading ability.

Other objects, features, and advantages of the present invention willbecome apparent to those skilled in the art from a consideration of thefollowing detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1a and 1b are plan views of exemplary visual stimuli displayed inaccordance with the present invention, particularly illustrating a testwindow with a test pattern superimposed over a background;

FIG. 1c is a plan view of text filtered in accordance with the presentinvention;

FIGS. 2a-2f are graphical views of data illustrating relationshipsbetween contrast sensitivity for direction discrimination with respectto spatial frequencies of the background for various subjects, includingdyslexic and normal children, particularly illustrating the relationshipat a spatial frequency of 0.5 cycle per degree of the test pattern;

FIGS. 3a-3f are graphical views of data illustrating relationshipsbetween contrast sensitivity for direction discrimination with respectto spatial frequencies of the background for various subjects, includingdyslexic and normal children, particularly illustrating the relationshipat a spatial frequency of 1.0 cycle per degree of the test pattern;

FIGS. 4a-4f are graphical views of data illustrating relationshipsbetween contrast sensitivity for direction discrimination with respectto spatial frequencies of the background for various subjects, includingdyslexic and normal children, particularly illustrating the relationshipat a spatial frequency of 2.0 cycles per degree of the test pattern;

FIGS. 5a-5f are graphical views of data illustrating relationshipsbetween contrast sensitivity for direction discrimination with respectto spatial frequencies of the background for various subjects, includingdyslexic and normal children, particularly illustrating the relationshipat a spatial frequency of 0.25 cycle per degree of the test pattern;

FIGS. 6a-6d are graphical views of data illustrating relationshipsbetween contrast sensitivity for orientation discrimination with respectto spatial frequency of the test pattern for various subjects;

FIGS. 7a-7c are graphical views of data illustrating relationshipsbetween an improvement in contrast sensitivity function for directiondiscrimination with respect to spatial frequency of the test pattern forvarious subjects;

FIGS. 8a-8c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 0.5 cycle per degreefor various subjects in Grade 1;

FIGS. 9a-9c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 0.5 cycle per degreefor various subjects in Grade 2;

FIGS. 10a-10c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 0.5 cycle per degreefor various subjects in Grade 3;

FIGS. 11a-11c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 1.0 cycle per degreefor various subjects in Grade 1;

FIGS. 12a-12c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 1.0 cycle per degreefor various subjects in Grade 2;

FIGS. 13a-13c are graphical views of data illustrating relationshipsbetween contrast sensitivity with respect to background spatialfrequency for a test-pattern spatial frequency of 1.0 cycle per degreefor various subjects in Grade 3;

FIGS. 14a-14c are graphical views of data illustrating relationshipsbetween reading rates with respect to filtered and unfiltered text forvarious subjects;

FIGS. 15a-15e are graphical views of data illustrating relationshipsbetween proportional improvements in reading rates with respect tofiltered and unfiltered test for various subjects;

FIG. 16 is a flowchart illustrating steps in exemplary methodology formeasuring and improving contrast sensitivity of a subject in accordancewith the present invention;

FIG. 17 is a perspective view of a computer system configured inaccordance with an exemplary embodiment of the present invention formeasuring and improving contrast sensitivity for motion discrimination;

FIG. 18 is a graphical view of a sinusoid, illustrating principles ofcontrast;

FIG. 19 is a schematic view of a subject and a monitor of the computersystem of the invention, illustrating principles of visual angle;

FIG. 20 is a flowchart of exemplary methodology of the present inventionfor improving contrast sensitivity for motion (or direction)discrimination;

FIG. 21 is a schematic view of visual stimuli, specifically a backgroundand a test pattern, displayed with a contrast and a spatial frequency inaccordance with the present invention, particularly illustrating thetest pattern in an initial position;

FIG. 22a is a schematic view of the background and the test pattern ofFIG. 21, particularly illustrating the test pattern in a second positionwhich is to the right of the initial position, in accordance with apreferred embodiment of the invention;

FIG. 22b is a schematic view of the background and the test pattern ofFIG. 21, particularly illustrating the test pattern in an alternativesecond position which is to the left of the initial position, inaccordance with a preferred embodiment of the invention;

FIG. 23 is a graphical view illustrating steps in an exemplary method ofthe present invention for determining a contrast-sensitivity thresholdof a subject at predetermined spatial frequencies of the test patternand the background; and

FIG. 24 is a graphical view illustrating exemplary contrast sensitivityfunctions (CSFs) of a normal adult, a normal child, and a dyslexicchild.

DETAILED DESCRIPTION OF THE INVENTION

Referring more particularly to the drawings, exemplary apparatus formeasuring and improving the contrast sensitivity for motiondiscrimination of a subject and configured in accordance with theteachings of the present invention is illustrated in FIG. 17 as acomputer system 100. Exemplary computer system 100 is configured tomeasure and also improve the contrast sensitivity for motiondiscrimination of a subject. Measuring contrast sensitivity for motiondiscrimination is used to determine whether a subject suffers from areading disorder, such as dyslexia. Improving contrast sensitivity formotion discrimination results in an improvement in reading ability and aremediation of the reading disorder. In other words, the presentinvention may be used to cure dyslexia. For purposes of this descriptionand without limiting the scope of the present invention, exemplarysystem 100 includes a computer 102 which is connected to output devicessuch as a visual output or monitor 104 and an audio output or speaker106. Computer 102 is also connected to input devices such as a keyboard108, a mouse 110, and/or a microphone 112.

Exemplary methodology of the invention may be implemented on the systemin the form of instructions stored as computer-readable code whichconfigures exemplary computer 102 to perform in accordance with thepresent invention. These instructions may be stored on computer-readablestorage media such as a compact disc read-only memory (CD-ROM) 114 or afloppy disc 116 for downloading into computer 102 through a CD-ROM drive118 or a floppy drive 120, respectively. Alternatively, thecomputer-readable instructions may be downloaded into computer 102through an Internet connection 122 as known in the art. In addition,computer 102 may include a hard disc 124 on which computer-readableinstructions may be pre-stored or "bundled" as known in the art.Exemplary computer system 100 may be configured as an IPC SPARCstationmanufactured by Sun Microsystems, including a high-resolution monitor(e.g., 1,160 pixels by 900 pixels and 256 levels of gray for each of thered, green and blue channels) and a high-speed computer (e.g., 16million instructions per second).

Exemplary computer 102 is configured to display on monitor 104 visualstimuli in the form of a background 130 and a test pattern 132. Testpattern 132 is displayed within a test window 134 which is superimposedover background 130. Both the background 130 and the test pattern 132are displayed with a contrast and a spatial frequency. As illustrated inFIG. 1a, exemplary background 130 and test pattern 132 may be displayedas a plurality of light and dark vertical stripes which alternate in asubstantially sinusoidal manner. Alternatively, as shown in FIG. 1b, thestripes may be horizontal. Other terminology describing the stripes maybe sine-wave gratings.

To discuss the respective contrasts at which the background 130 and thetest pattern 132 are displayed, reference is made to FIG. 18. Contrastmay be defined as the ratio between the lightest or the darkest portionof the stripes and the mean value of the stripes, compared to the meanvalue of the stripes. This difference is shown as δ, and the mean valueis defined as the gray level of the light and dark stripes. Accordingly,a contrast of 5% indicated that the brightest portion of the lightstripes (i.e., the peak) are 5% lighter than the average gray level, andthat the darkest portion of the dark stripes (i.e., the troughs) are 5%darker than the average gray level.

To discuss the spatial frequencies of the background 130 and the testpattern 132 in more detail, reference is made to FIG. 19. The respectivespatial frequencies at which the background 130 and the test pattern 132are displayed may be defined as the rates at which the respectivestripes repeat. A subject 136 of whom contrast sensitivity for motiondiscrimination is to be measured is positioned a distance d from monitor104. A visual angle α accordingly exists between the subject 136 and themonitor 104. In accordance with the present invention, the subject 136is positioned with respect to the monitor 104 such that visual angle αis defined to be 1 degree for about every 1 centimeter (cm) of arclength λ. To yield such a relationship between visual angle α and arclength λ, the subject 136 is positioned about 57 cm from the monitor 104(i.e., distance d is about 57 cm). In this regard, the respectivespatial frequencies at which the background 130 and the test pattern 132are displayed are measured in cycles per degree (of visual angle). Forexample, if the spatial frequency of the test pattern 132 is 1 cycle perdegree (cpd), then there would be one light stripe and one dark stripefor about every 1 cm on the monitor 104 when the subject 136 ispositioned about 57 cm away. As shown in FIG. 1a, the background 130 isbeing displayed at about 2 cpd while the test pattern is being displayedat about 1 cpd.

Exemplary background 130 and test pattern 132 have a spatialrelationship with respect to each other in that the background issubstantially larger than the test pattern, for example, on the order ofabout 5 times larger. In terms of the visual angle, the background 130may be displayed on monitor 104 to subtend about 20 degrees of visualangle, while the test pattern 132 may be displayed to subtend about 4degrees of visual angle. The test window 134 is preferably centeredwithin the background 130 and in the form of a familiar shape forchildren, for example, a fish. Generally speaking, exemplary test window134 is substantially circular.

The contrast at which the background 130 is displayed and the contrastat which the test pattern 132 is displayed are selected from apredetermined range of contrasts which stimulate the visual corticalmovement system of the subject 136. As known, the visual corticalmovement system of humans includes the magnocellular neurons asdescribed above and is selectively stimulated by contrasts which areless than about 10%. In accordance with the present invention, exemplarybackground 130 is displayed with a constant contrast of about 5%, andexemplary test pattern 132 is displayed at a contrast ranging from 0% toabout 10%, which will be discussed in more detail below.

The spatial frequency at which the background 130 is displayed and thespatial frequency at which the test pattern 132 is displayed areselected from a predetermined range of spatial frequencies whichstimulate the visual cortical movement system of the subject 136. Inaccordance with the present invention, the spatial frequency at whichexemplary test pattern 132 is displayed is less than about 5 cycles perdegree (cpd), and the spatial frequency at which exemplary background130 is displayed is a few octaves higher and a few octaves lower thanthe spatial frequency of the test pattern; in other words, thebackground spatial frequency is centered about the test-pattern spatialfrequency. For example, if the spatial frequency of the test pattern 132is about 1 cpd, then the spatial frequency of the background 130 mayrange from about 1/4 cpd, 0.5 cpd, 1 cpd, 2 cpd, and 4 cpd (see FIGS.3a-3f); if the test-pattern spatial frequency is about 0.25 cpd, thenthe background spatial frequency may range from about 0.0625 cpd, 0.125cpd, 0.25 cpd, 0.5 cpd, and 1 cpd (see FIGS. 5a-5f).

In accordance with the present invention, to measure the contrastsensitivity for motion discrimination of the subject 136, exemplarycomputer system 100 is configured to implement an interactive processemploying a two-alternative forced choice task. The methodology of thepresent invention is generally represented by the flowchart of FIG. 20,which includes a preliminary initialization step (block S10) which willbe discussed below. Referencing FIG. 21, upon activation, for example,by the subject 136 manipulating the mouse 110, exemplary computer 102displays on monitor 104 a background 130 with a contrast (e.g., about5%) and a spatial frequency (e.g., about 0.5 cpd) and a test pattern 132within test window 134 with a contrast (e.g., about 5%) and a spatialfrequency (e.g., about 1 cpd) (block S12). One of the dark stripes ofthe background 130 is referenced with numeral 140, and one of the darkstripes of the test pattern 132 is reference with numeral 142. Thecomputer 102 will then move the test pattern 132 within the test window134 (block S14). For example, in FIG. 22a the test reference stripe,which is indicated by numeral 142', is positioned to the right of whereit was initially (i.e., as shown in FIG. 21), and in FIG. 22b the testreference stripe, which is indicated by numeral 142", is positioned tothe left of where it was initially. Exemplary computer 102 may randomlyselect to move the test pattern 132 either to the right or the left.Although the test pattern 132 may be moved in any desired degree orlength, it is preferable to shift the stripes either left or right adistance substantially equal to about one-half of the width of one ofthe stripes, which is equal to about 90 degrees of spatial frequency,which can be seen in FIGS. 20 and 22. (For the sake of clarity, thestripes of the background 130 and the test pattern 132 alternate inaccordance with a square wave, rather than a sinusoid, in FIGS. 20 and22.)

Both the initial position of the test pattern as shown in FIG. 21 andthe moved position of the test pattern as shown in either FIG. 22a or22b are displayed for a predetermined period. The periods for which thetest pattern is displayed in each position is for a length which causesapparent motion of the stripes of the test pattern. Apparent motion ofthe stripes of the test pattern 132 may be induced in the subject 136when the test pattern displayed in the initial position (as in FIG. 21)and the test pattern displayed in either of the final positions (asshown in FIGS. 22a and 22b, with apparent motion indicated by arrows Rand L, respectively) for less than about 2/10 second, for example. In apreferred embodiment of the invention, the test pattern 132 is displayedin both the initial and final positions for about 150 milliseconds (0.15seconds).

Before displaying the initial position of the test pattern 132 and afterdisplaying the final position of the test pattern (i.e., before andafter moving test pattern), computer 102 does not display the background130 or the test window 134 on monitor 104, in that it may be preferablefor the monitor to be blank or to display all the pixels with a grayvalue. Alternatively, the background 130 may remain displayed on themonitor 104 with only the test window 134 being blank. Exemplarycomputer 102 may store images of the test pattern 132 in the initialposition shown in FIG. 21 and in each of the possible final positions asshown in FIGS. 22 in files in memory. To display the computer 102 mayoutput the image file of the test pattern 132 in the initial positionfor the predetermined period and then output either of the image filesof the test pattern 132 in the final position for the predeterminedperiod. When image files are not output by the computer 102, the monitor104 does not display any image. The image files may be in the form ofpixel maps (i.e., pixmaps) as known in the art.

After moving the test pattern 132 within the test window 134 (i.e.,after displaying the test pattern in one of the final positions),exemplary computer 102 is configured to receive a signal from thesubject 136 indicative of the direction the subject believes the testpattern moved (block S16). The subject 136 may provide the signalthrough one of the input devices, that is, the keyboard 108, the mouse110, or the microphone 112. The computer 102 may prompt the subject 136for a response, for example, with a graphical user interface on themonitor 104 or with an audible through the speaker 106. Alternatively,the subject 136 may be initially instructed to input the signal when themonitor 104 is blank after the final position of the test pattern 132 isdisplayed. In a preferred embodiment of the invention, the subject 136may use the mouse 110 which has a plurality of input buttons, includinga right button 144R and a left button 144L. If the subject 136 believesthat he or she saw the test pattern 132 move to the right, then thesubject may press right button 144R of the mouse 110 to provide thesignal. If the subject 136 believes that he or she saw the test pattern132 move to the left, then the subject may press the left button 144L toprovide the signal.

Upon receiving the signal, the computer 102 determines whether thesubject 136 is correct or not in perceiving the movement of the testpattern 132. If the computer 102 displayed the test pattern 132 in theright final position shown in FIG. 22a and the subject 136 pressed theright button 144R, or if the computer displayed the test pattern 132 inthe left final position shown in FIG. 22b and the subject pressed theleft button 144L, then the computer 104 would determine that the subjectinput a correct signal. Conversely, if the computer 102 displayed thetest pattern 132 in the right final position shown in FIG. 22a and thesubject 136 pressed the left button 144L, or if the computer displayedthe test pattern 132 in the left final position shown in FIG. 22b andthe subject pressed the right button 144R, then the computer 104 woulddetermine that the subject inputted an incorrect signal. In response toreceiving a signal from the subject 136, the computer 102 modifieseither the contrast of the test pattern 132 or the spatial frequency ofeither the background 130 or the test pattern 132 (block S18), asdiscussed below.

If the signal input by the subject 136 is correct, then the computer 102may, for example, decrease the contrast of the test pattern 132, therebymaking it more difficult to distinguish the light and dark stripes.After modifying the test pattern contrast, the computer 102 may thenredisplay the background 130 (the contrast and the spatial frequency ofwhich has not been modified in this example) and display the testpattern 132 with the same spatial frequency as initially displayed andwith the decreased contrast (loop S20 and block S12). After thepredetermined period (e.g., 150 msec), the computer 102 moves testpattern 132 with the modified contrast within the test window 134 (blockS14), awaits to receive a signal from the subject 136 (block S16), andmodifies the contrast of the test pattern 132 again and/or the spatialfrequency of either the background 130 or the test pattern (block S18).This process may repeat a plurality of times. Although any specifiedrange may be possible which stimulates the visual cortical movementsystem of the subject 136, in a preferred embodiment of the inventionthe contrast of the test pattern 132 may vary between, for example, 5%and 0.5% at 0.5% increments (i.e., 5%, 4.5%, 4.0%, . . . 0.5%), and mayinclude 0.25% and any other desired contrast as well.

Rather than decreasing the contrast of the test pattern 132 in responseto a correct signal, the computer 102 may modify the spatial frequencyof the background (block S18). For example, if the test pattern 132 isbeing displayed at a spatial frequency of about 1 cycle per degree(cpd), then the computer 102 may modify the spatial frequency of thebackground from 2 octaves lower or 0.25 cpd, 1 octave lower or 0.5 cpd,the same or 1 cpd, 1 octave higher or 2 cpd, to 2 octaves higher or 4cpd. After modifying the spatial frequency of the background 130, thecomputer 102 may then display the background 130 as modified and thetest pattern 132 and move the test pattern within the test window(blocks S12 and S16) as described above. At each of these backgroundspatial frequencies, the computer 102 may increase or decrease thecontrast of the test pattern 132 a plurality of times in response tocorrect or incorrect signals.

Also in response to a correct signal, the computer 102 may modify thespatial frequency of the test pattern 132 (block S18). For example, ifthe test pattern 132 is being displayed with a spatial frequency ofabout 0.5 cpd, then the computer 102 may increase this frequency 1octave to 1 cpd. In accordance with a preferred embodiment of thepresent invention, the test pattern 132 may be displayed at a spatialfrequency selected from a range of predetermined frequencies including0.25 cpd, 0.5 cpd, 1.0 cpd, and 2.0 cpd. After modifying the spatialfrequency of the test pattern 132, the computer 102 may then display thebackground 130 and the test pattern 132 as modified and move themodified test pattern within the test window 134 (blocks S12 and S16) asdescribed above. At each of these test pattern spatial frequencies, thecomputer 102 may increase or decrease the contrast of the test pattern132 and/or the spatial frequency of the background 130.

The inventor has discovered that by repeatedly following the methodillustrated by the flowchart of FIG. 20 that the contrast sensitivityfor motion (or direction) discrimination of the subject 136 willincrease. When this contrast sensitivity increases, the reading abilityof the subject 136 increases. (Contrast sensitivity, which will bediscussed in more detail below, is defined as the inverse of contrastthreshold, which is the minimum contrast at which the subject candistinguish sideways movement.) The subject 136 may be a child withso-called normal reading ability or any other person--adult orchild--who suffers from one form of dyslexia or another. As dyslexia ofvarious degrees and types may afflict as much as 50% of the populationas a whole, the benefit to society is essentially boundless. Although itis often preferable to initially measure the contrast sensitivity formotion discrimination of the subject 136, this measurement does not needto be undertaken in order to improve the contrast sensitivity.

In many applications of the present invention, schools, for example, maymake the present invention available to first and second graders forpractice. To entice such young children to practice, the presentinvention may be configured as a "fish game" in which the object of thegame is being able to answer correctly the question, "Which way did thefish stripes move?" As they play the fish game, the children improvetheir contrast sensitivity for motion discrimination and thereby improvetheir ability to read. If the child is dyslexic, the improvement will begreat; whereas if the child is of normal vision or reading ability, theimprovement will be less marked. In any case, if all the children of agrade-school class play the game, it is not necessary to determine whichchildren are dyslexic as all children improve. The inventor hasdetermined that playing the fish game for as little as about 5 minutesto 10 minutes a week for about 8 weeks significantly improves contrastsensitivity for motion discrimination. As the computer-readableinstructions for configuring computers to operate in accordance with thepresent invention may be readily provided via conventional storage media(e.g., CD-ROM 114 or floppy disc 116) or via an Internet connection 122,and as the present invention uses visual exercises (e.g., the left-rightmovement of vertical stripes) rather than language to improve readingrates, schools and organizations all over the world may implement thefish game to improve the reading rates of children regardless ofeducational or ethnic backgrounds.

The methodology of the present invention has been described thus far ina general sense in that the test pattern 132 is moved with respect tothe background 130, a signal is received from the subject, and thecontrast and/or the spatial frequency of the test pattern 132 or of thebackground 130 is modified, with the process being repeated a pluralityof times to improve contrast sensitivity for motion discrimination. Amore specific and preferred embodiment of the present invention isillustrated in FIG. 16 which, in addition to improving contrastsensitivity, measures contrast sensitivity for motion discrimination anddetermines the contrast sensitivity function (CSF) for motiondiscrimination for the subject 136. To measure CSF, a staircaseprocedure is implemented to determine a contrast-sensitivity thresholdfor each spatial frequency of the test pattern 132 at each spatialfrequency of the background 130.

Exemplary methodology for measuring contrast sensitivity as illustratedin FIG. 16 may include a plurality of preliminary initialization steps.For example, data on the observer or subject 136 may be input into thesystem 100 (block S20), including name, date of birth, visual acuity(i.e., 20/20, etc.), viewing distance d, and so on. Parameters of themonitor 104 may also be entered into the system 100 (block S22), such ascolor and gamma functions. Contrast sensitivity function (CSF)parameters may also be initialized (block S24), which may include thegeneration of the visual stimulus patterns for the spatial frequenciesof the background 130 and the test pattern 132.

The computer 102 may then generate image files for the background 130and the test pattern 132 in the form of pixel maps or pixmaps (blockS26). As described above, the pixmaps may include the test pattern 132in the initial position (see FIG. 21), in a right position (see FIG.22a), and in a left position (see FIG. 22b), as well as a pixmap for thebackground 130. Generally speaking, the present invention measures andimproves contrast sensitivity for motion discrimination, whichspecifically includes direction (i.e., left-right) discrimination andorientation (i.e., vertical-horizontal) discrimination. Accordingly, thepixmaps may also include the test pattern 132 in a vertical position andin a horizontal position (see FIG. 1b). The pixmaps may then be copiedto the monitor 104 (block S28) as described above. Although variable,the pixmap for the background 130 may be displayed at a preferredcontrast of, e.g., 5% and a specified spatial frequency. The testpattern 132 is displayed at a specified contrast and spatial frequency.

With additional reference to FIG. 23, to determine thecontrast-sensitivity threshold of the subject 136 for a specifiedtest-pattern spatial frequency f_(T) (e.g., 0.25 cpd, 0.5 cpd, 1 cpd,and 2 cpd) at a specified background spatial frequency f_(B), thespatial frequencies at which the test pattern 132 and the background 130are displayed are held constant, while the contrast at which the testpattern is displayed is, varied, as shown on the vertical axis. Forexample, if the subject 136 indicates a wrong direction (block S30), thecontrast of the test pattern 132 is increased (block S32) one step,e.g., from 3.5% to 4% (while holding the spatial frequency constant),until the subject 136 indicates the direction correctly.

It is then determined whether the subject 136 is on the staircase (blockS34). This is determined when the subject 136 incorrectly indicates thedirection the test pattern 132 moves. For example, as shown in FIG. 23,the subject 136 correctly indicated the direction of the test pattern132 when displayed with contrasts of 5%, 4.5%, and 4%, as indicated by a"Y" for trial Nos. 1, 2, and 3. When the subject 136 incorrectlyindicates the direction, as shown by the "N" at trial No. 4, the subjectis on the staircase, and the contrast of the test pattern 132 isincreased one step (block S32), for example, from 3.5% to 4%. The pixmapwith the test pattern 132 with a 4% contrast is then copied to themonitor 104 for display (block S28). If the subject 136 correctlyidentifies the direction the test pattern 132 moved within the testwindow 134 at the 4% contrast (as indicated by the "Y" at trial No. 5 inFIG. 23), then the computer 102 determines whether a predeterminednumber of correct responses have been made, for example, three (blockS36). If not, then the computer 102 will redisplay the test pattern withthe same contrast (e.g., 4%) until the subject 136 indicates thedirection correctly for the predetermined number of times, such as threeindicated by the "Ys" at trial Nos. 5, 6, and 7.

It is then determined whether a predetermined number of inversions havebeen completed (block S40), which will be discussed in more detailbelow. If the predetermined number of inversions have not beencompleted, then the test-pattern contrast is decreased another step(block S38), for example, from 4% to 3.5%. If the subject 136incorrectly indicates the direction at this new test-pattern contrast,then the contrast remains the same (blocks S30, S36, and S28), forexample, at 3.5%. If the subject indicates the direction incorrectly atthis contrast, as indicated by the "N" at trial No. 9 in FIG. 23, thenthe contrast of the test pattern increases one step. This switching froma higher contrast to a lower contrast and from a lower contrast to thehigher contrast (e.g., 3.5% to 4% and 4% to 3.5%) is defined as aninversion. A run is initiated and terminated at an inversion. Thecomputer 102 monitors the number of runs which occur in determining thethreshold of the subject 136 for the particular spatial frequencies ofthe test pattern and the background, with the threshold being defined asthe lower contrast of the run. The predetermined number of runs in theexample shown in FIG. 23 is six, with each inversion indicated by trialNos. 1-4, 4-7, 7-9, 9-12, 12-13, and 13-16. Accordingly, for the exampleillustrated in the drawings, the contrast-sensitivity threshold for thesubject 136 at a test-pattern spatial frequency f_(T) and a backgroundspatial frequency f_(B) is 3.5%.

Once the predetermined number of inversions have been completed (blockS40), the data (such as those graphically illustrated in FIG. 23) areanalyzed (block S42) to determine the contrast-sensitivity threshold atthe specified spatial frequencies. If the subject 136 has not yetcompleted testing at all of the predetermined spatial frequencies of thebackground 130, that is, two octaves higher and two octaves lower than,as well as equal to, the test-pattern spatial frequency as describedabove (block S44), then the computer 102 may add a stimulus (block S46),for example, an audible signal, indicating that the subject 136 hascompleted one specified test-pattern spatial frequency at one backgroundspatial frequency, and will begin, for example, testing at anotherbackground spatial frequency for the same test-pattern spatialfrequency. Accordingly, the CSF for the new frequencies may then beinitialized (block S24).

This process is repeated until the subject 136 has been tested for allof the predetermined background spatial frequencies for the specifiedtest-pattern spatial frequency (block S44). The data for the specifiedtest-pattern spatial frequency may then be stored (block S50) togenerate a contrast sensitivity function (CSF) for the specifiedtest-pattern spatial frequency, as illustrated in FIG. 24. Contrastsensitivity (the vertical axis) is the inverse of contrast-sensitivitythreshold. For example, in the example shown in FIG. 23, acontrast-sensitivity threshold of 4% (i.e., 0.04) yields a contrastsensitivity of 25. FIG. 24 exemplifies the CSF of a normal adult, anormal child, and a child with dyslexia As can be seen, the dyslexicchild has lower contrast sensitivities than the normal child, especiallywhen the background spatial frequency f_(B) equals the test-patternspatial frequency f_(T), which will be discussed in more detail below.

If the subject 136 has not been tested for all of the predeterminedtest-pattern spatial frequencies after completing the testing for aparticular test-pattern spatial frequency (block S52), then thetest-pattern spatial frequency is modified (e.g., increased or decreasedwithin the preferred predetermined range of 0.25 cpd, 0.5 cpd, 1 cpd,and 2 cpd) (block S54), and the process returns to block S24.

The preferred methodology described thus far measures the CSFs of thesubject 136. In addition, by being tested, that is, by repeatedlywatching the test pattern 132 shift left and right at the predeterminedcontrasts and spatial frequencies, the CSFs of the subject improve. Forexample, if the subject 136 has a CSF like that of a dyslexic childshown in FIG. 24, then the process of being tested (i.e., playing thefish game) improves the contrast sensitivities of the dyslexic child.The inventor has discovered that by repeating the test in the future(block S56), for example, once or twice a week for up to eight weeks,significantly improves the CSFs of all children, but especially indyslexic children, so that the CSF of a dyslexic child will be reshapedto look like the CSF of a normal child (see FIG. 23). The testingprocess may be repeated for a plurality of subjects (block S58).

The above-described apparatus and methodology of the invention iscapable of being alternatively configured for many applications. Forexample, rather than being displayed at a single spatial frequency atone time, the background 130 may be displayed with a plurality ofspatial frequencies, e.g., as a natural scene. This is particularlybeneficial in testing children in that the fish game may be implementedmore realistically with the fish-shaped test window 134 "swimming"through a natural aquatic background 130. Additionally, although thepresent invention has been described in relation to the contrastsensitivity for direction discrimination, the principles of the presentinvention may be readily applied to measuring and improving contrastsensitivities for all motion discrimination of the visual corticalmovement system.

The principles of the present invention are further exemplified in theexamples which follow.

EXAMPLE

The following examples investigate whether entertaining visual exerciseimproves the reading performance of both normal and dyslexic children ingrades 1 to 3. This task was entertaining by using a familiar object(e.g., a striped fish) in an unfamiliar task. The visual exercise wasprovided by using auditory feedback to enable the child to quickly learnto see dim stripes that moved to the left or to the right. This studyrevealed the importance of mapping out direction discrimination CSFs fora four-octave range of background frequencies centered around testfrequencies spanning four octaves, from 0.25 cpd to 2 cpd, for bothrapid screening and remediation. One octave is a doubling in frequency.

Testing was performed on a random sample of children aged 5 to 8 yearsold from a local elementary school. Children were included in the studyif they had 20/20 visual acuity, normal intelligence, as verified bystandardized tests administered by the school, no known organicdisorders, and no known behavioral disorders. Only one-third of theKindergarten children were included in this study. The other two-thirdsof the Kindergarten children could not push a mouse button whilemaintaining fixation on the screen, thereby being unable to perform the2AFC task for measuring the CSF. The sample of students who participatedin this study in grades 1 to 3 was a diverse population representativeof the range of normal children in each class tested, as verified by theschool's principal who was also the learning specialist, and eachteacher. A total of 35 children were included in this study, fivechildren in kindergarten, ten children in first grade, five normalreaders and five children with reading problems in each of grades 1 to3. Five children were used in each group, so that a completelycounterbalanced design was used, distributing the variability equallyacross different grade levels and type of reader.

A standardized reading test The Dyslexia Screener (TDS) was used todetermine whether a child was a normal reader. Data were collectedduring the normal school day, during non-directed teaching time, whichwas usually during computer lab. By testing children during school hoursboth normal readers and children with reading problems were able to betested at regular weekly intervals. Each child was tested each morningfrom 8 o'clock to 12 noon with sessions lasting from 5 to 10 minutesonce per week. A subset of the practiced observers, i.e., m1, a1, s1,l1, who were dyslexic required one eye to be patched for about one monthto establish eye dominance. Otherwise, test patterns, especially thosethat were low frequency, appeared to oscillate back and forth, insteadof moving in one direction. The CSFs for the normal adult in both CSFtasks were the average of a male and a female both 43 to 44 years old,with 20/20 acuity and normal intelligence.

All observers sat at a viewing distance of 57 cm from the screen for alltasks in this study, enabling high spatial frequencies up to 8 cyc/degto be displayed. During the first session, the student's visual acuitywas measured with a hand-held eye chart The TDS was administered todetermine the child's reading grade level and whether the childexhibited reading problems. The observer's CSF to discriminate betweenorthogonally oriented brief 150 msec patterns was measured. It took twoto three sessions to measure each child's orientation discriminationCSF. This CSF was then used to generate individualized filtered textthat was stored on the hard disk.

Reading rates for equal size filtered and unfiltered text were measuredin a subsequent session. Reading rates were used to evaluate a child'sreading performance, since this task relies on a child's ability todecode words, and cues such as context affect performance. Text waschosen that was entertaining, and easy to read, so that the difficultyof the text did not limit reading performance. The directiondiscrimination CSFs were measured, following the reading rate session,once a week for the next 8 weeks, each week the CSF for a new testfrequency was mapped out for a 4-octave range of background frequencies.Therefore, each replication for a particular set of test and backgroundpatterns was spaced about one month apart.

Approximately half of the children in grades 1 to 3 were tested on thedirection discrimination task from 12 to 20 weeks. Only these childrenhad the benefit of more than one practice threshold, and their data areplotted accordingly in the graphs depicting individual data. Finally, inthe last three sessions, reading rates for both unfiltered and filteredtext, having a high mean luminance, 67 cd/m², as used for all tests upto this point, and a low mean luminance of 8 cd/m², to enable grayscaleand colored text, red, green, blue, and yellow, to be set to equivalentmean, minimum, and maximum luminances, were measured. A questionnairewas administered during the last session to determine whether thestudent liked being tested and whether the student noticed anyimprovements in their visual function and/or reading performance.

Direction-discrimination contrast sensitivity functions (CSFs) weremeasured to provide interactive training using a temporal twoalternative forced choice (2AFC) task with feedback During thesesessions, a test pattern of a vertical sine-wave grating was presentedin the form of a fish, as shown in FIG. 1a, with the fish-shaped testpattern subtending 4 degrees of visual angle at a viewing distance of 57cm. The edges of the test pattern provided the outline of the fish thatwas surrounded by a circular background of a vertical sine-wave grating.The test patterns and backgrounds were presented abruptly for 150milliseconds (msec) using simultaneous metacontrast. The verticalstripes covering the fish were moved by phase shifting each stripe by 90degrees either to the left or the right from one 150-msec interval tothe next The subject was asked to identify the direction of motion, thatis, whether the stripes moved to the left or to the right, by pressingone of two mouse buttons indicating direction. Initially, test andbackground spatial frequencies were presented at a 5% contrast. Thesubject initiated the practice session by pushing the middle mousebutton. During the practice session, the contrast of the fish patternwas increased one step on each incorrect response; otherwise thecontrast remained constant. When the subject felt comfortable with thetask, the middle mouse button was pushed again to begin the testsession.

The only difference between the test and the practice session was thateach time the subject chose the direction of movement correctly, thecontrast of the test pattern was reduced one step until the firstincorrect response. A 2AFC double-staircase psychophysical procedure asknown in the art was then initiated to measure the contrast thresholdneeded to detect the left-right movement correctly at least 79% of thetime. This 2AFC psychophysical task enabled measuring the mostsensitive, repeatable contrast thresholds possible. The subject wasinstructed when to progress from the practice session to the testsession. About three practice trials were completed before moving to thetest session. Each threshold consisted of approximately 20 to 30 trials.

Sine-wave gratings of 0.25 cycle per degree (cpd), 0.5 cpd, 1.0 cpd, and2 cpd were used to characterize the fish-shaped test pattern. Each ofthe sine-wave gratings was surrounded by one of five different sine-wavebackgrounds. The spatial frequency of the background may be equal to thespatial frequency of the test pattern, or may be one or two octaveshigher or lower than the spatial frequency of the test pattern. Subjectswere given auditory feedback, one short beep or three short beeps,indicating whether the direction of the motion had been correctlyidentified. This auditory feedback was used to train the subject todiscriminate left and right movement at low contrasts.

Vertical sine-wave gratings were used to map out the contrastsensitivity function (CSF) of each subject to discriminate left-rightmovement. Initially, both the test pattern and the background weredisplayed at 5% contrast to optimally activate magnocellular neurons.The background and the test pattern were displayed for a short durationof about 150 msec to optimally activate magnocellular neurons andprevent eye movement. The CSFs for direction discrimination were thesame for patterns that were presented for 750 msec or 150 msec. Thedirection discrimination contrast thresholds were grouped into thelowest and highest values and plotted accordingly to show the effects ofpracticing left-right discrimination one time for each stimulus pattern.

Orientation discrimination CSFs were measured to map the CSF for a5-octave range of spatial frequencies, from 0.25 cpd to 8.0 cpd, so thatthe CSF for high spatial frequencies could be used to generate filteredtext. The test pattern was a circular fish which subtended a visualangle of 8 degrees at a viewing distance of 57 cm as shown in FIG. 1b.The subject's task was to push a key indicating whether the abruptlypresented (e.g., 150 msec) test pattern was vertical (i.e., up or down)or horizontal (i.e., sideways) in orientation. Auditory feedback wasgiven after each pattern to indicate whether the subject chose theorientation of the pattern correctly. A 2AFC staircase procedure wasused to measure the contrast threshold function of each subject.Following a short practice session that set the initial contrast of thetest pattern, the test run was initiated. At the beginning of the testrun, the contrast of the test pattern was decreased one step of 0.5%,each time the observer correctly identified the orientation of the testpattern. Following the first incorrect response, the staircase procedurewas used. In the staircase, the subject had to correctly identify theorientation of the test pattern three times in a row before the contrastwas decreased one step. The contrast was increased one step each timethe orientation of the test pattern was identified incorrectly. Eachthreshold consisted of approximately 20 to 30 trials.

Based on an assumption is that reading relies on the low-resolutionmovement system, the present invention evaluates the movement system bymeasuring the contrast sensitivity for motion discrimination of asubject. From this perspective, dyslexia, which may be defined as adifficulty in reading in a child of normal intelligence and anadult-level acuity (i.e., 20/20) but with low contrast sensitivity formotion discrimination, is explained as a difficulty in visuallyperceiving words on a page that could be readily decoded otherwise.Tests of the acuity system, such as visual acuity using long-durationpatterns, reveal no differences between children with normal reading andchildren with reading problems. In contrast, differences betweenchildren with normal reading and children with reading problems arerevealed only by tests of the visual cortical movement system.

Reading rates were measured for continuously scrolled text both beforeand after measuring Contrast Sensitivity Functions (CSFs) todiscriminate left-right movement for 35 normal children aged 5 to 8years old. When compared to age-matched normal readers, thedirection-discrimination CSFs were 3 to 4 times lower for dyslexics andresembled the CSFs of 5-year-old children. Moreover, the CSFs of normaland dyslexic children revealed a different pattern of results when testand background frequencies were equal, thereby enabling rapid screeningfor dyslexia at 6 and 7 years old.

Humans form memories after single experience by "rewiring" circuits inthe brain. Perceptual learning, which refers to the ability ofexperience to alter the sensitivity or timing of one's perceptualmachinery, is a form of memory that resides within the circuits in thebrain that process sensory information. Experience dependent changes inthe numbers of neurons and synaptic connections have been observed inthe visual cortex even as early as primary visual cortex. Experience mayhave particularly strong and rapid affects on the developing visualcortex and is also capable of affecting the mature nervous system.

The circuits that underlie motion discrimination are plastic and can berewired by experience. Accordingly, practicing the task used to measurecontrast sensitivity for motion discrimination increases the subject'scontrast sensitivities. To rapidly remediate reading disorders, asubject repeats the above-described method for about 5 minutes to 10minutes per week for about eight weeks. By using feedback and practice,the subject will significantly improve motion discrimination CSFs up to8 fold on average and reading rates up to 9 fold on average. Theevidence that is presented below support the concept that networks inmagnocellular streams play a major role in reading and are maturing inall 5- to 8-year-old children. Since rapid remediation was found using adirection discrimination task, the most rapid remediation occurring for6- to 7-year-old children, which indicates that these children aretransitioning through a critical period for movement discrimination atthat age.

Dyslexics have anomalies in their magnocellular networks, demonstratedby: (1) higher contrast thresholds to detect brief patterns, (2) animpaired ability to discriminate both the direction and the velocity ofmoving patterns, and (3) unstable binocular control and depthlocalization when compared to age-matched normals. Dyslexics hadselective deficits in the magnocellular layers of both the visual(lateral geniculate nucleus) and auditory (medial geniculate nucleus)regions of the thalamus. However, there were no deficits in theparvocellular regions of the thalamus. Losses in the responsiveness ofthe magnocellular neurons found in the lateral geniculate nucleus ofdyslexics will affect all subsequent levels of processing that receiveinput from these magnocellular neurons. Brain recordings usingfunctional Magnetic Resonance Imaging (fMRI) found that when dyslexicswere compared to normal controls, there were clear deficits to movingpatterns in the fMRI activation of all extrastriate visual areas, mostnoticeably of the visual-motion area or Medial Temporal cortex (MT),where the MT failed to be activated by coherently moving random dotpatterns that produced a large response in non-dyslexic counterparts.

Reading rates were measured for continuous scrolled text both before andafter the measurement of contrast sensitivity functions (CSFs) todiscriminate left-right movement and were measured for 35 normalchildren aged 5 to 8 years old. When compared to age-matched normalreaders, the direction discrimination CSFs were 3 to 4 fold lower fordyslexics, with the CSFs of dyslexics resembling the CSFs of 5-year-oldchildren.

The direction discrimination CSFs illustrated in FIGS. 2 to 5 show thatmovement discrimination is developing in all normal children. Thedirection discrimination CSFs of normal children were 2 to 8 fold lowerthan a normal adult's CSF, whereas the CSFs of dyslexic children were 8to 17 fold lower than a normal adult's CSF seen by comparing originalCSFs (orig.) with the CSFs of the practiced observer after 1 practice(1prac.) and 2 or more practice (2prac.) contrast thresholds.

When patterns that test a child's ability to discriminate movement areused to measure the child's CSF, differences between children and adultson the order of 10 times are obtained which was not found previouslyusing long-duration patterns. This same pattern of results was found foreach of the 4 test frequencies, as shown in FIGS. 2-5, spanning therange of spatial frequencies that optimally activate magnocellularneurons.

The CSFs of normal and dyslexic children clustered into 2 separategroups. The direction discrimination CSFs revealed a 3- to 4-fold (i.e.,300% to 400%) difference between dyslexics and age-matched normals,whereas orientation discrimination CSFs revealed a 2-fold differencebetween good and poor readers. This difference between dyslexic andage-matched normal children was significant in both tasks, p<0.001 andp<0.003, respectively, when analyzed using a Student's t-test for twosamples having unequal variance. The much lower CSFs for dyslexic thanfor age-matched normal readers indicate that a child's directiondiscrimination CSFs are closely related to their reading ability.

There were no differences between the CSF results of children withreading problems aged 6 to 8 years old and a normal 5-year-old child. Infact, the CSF of a child with reading problems was usually lower thanthe CSF of a 5-year-old child. Thus, these CSFs show that thedevelopment of movement discrimination is still developing in allchildren, appearing to be arrested in development for dyslexic children.

Previous studies that investigated the detection of brief patterns orvelocity discrimination using random dot patterns obtained CSFs thatonly revealed a 0.3-fold (30%) difference between good and poor readers,instead of the 3- to 4-fold differences in the direction discriminationCSFs that were found in this study. When tasks do not activate movementdiscrimination channels optimally, then not only are much smallerdifferences between dyslexic and age-matched normal readers found, butalso the difference between dyseidetic and normal readers disappearsaltogether. When the direction discrimination task was used, there wereno significant differences between different types of dyslexic readers,all types having 3 to 4 fold lower CSFs than age-matched normalchildren. Therefore, this study revealed the importance of mapping outdirection discrimination CSFs for a four-octave range of backgroundfrequencies centered around test frequencies of 0.25, 0.5, 1, and 2cycles per degree (cpd) for rapid and effective screening.

The direction discrimination CSFs for patterns having a test frequencyof 0.25, 0.5, 1, and 2 cpd are ideal to use for dyslexia screeningbecause (1) normal children had the highest CSF, whereas dyslexicchildren had the lowest CSF, when test and background frequencies wereequal, and (2) as the test frequency was increased, the 3-folddifferences in the CSFs between dyslexic and normal children increased,as shown in FIG. 7a.

The CSFs for high test and background frequencies when discriminatingleft-right movement revealed the largest difference between bothchildren and adults, and dyslexic and age-matched normal children. Theseresults demonstrate that the motion networks are still maturing in 5- to8-year-old children when conducting tasks such as directiondiscrimination. In addition, this study shows that dyslexics haveimmature networks, with their CSFs being lower than a practiced normal 5year old. After five years of age, normal readers have directiondiscrimination (DD) CSFs that show a peak when the test and backgroundfrequencies are equal, whereas children with reading problems show atrough when the test and background frequencies are equal.

The CSFs of normal and dyslexic children reveal a different pattern ofresults when test and background frequencies were equal, therebyenabling rapid screening for dyslexia at 6 to 7 years old. The spatialfrequency combinations that revealed the largest differences betweenboth children and adults and between children with normal reading andchildren with reading problems were when background frequencies wereequal to or greater than the test frequency.

The direction discrimination CSFs revealed a more reliable means toscreen for dyslexia. Not only were CSFs for children with readingproblems 3 to 4 times lower than age-matched children with normalreading, a different pattern of results for these two groups was found.All dyslexic children had significantly lower CSFs (p<0.005) when testand background frequencies were equal, whereas for practiced normalchildren and normal adults, CSFs were highest when test and backgroundfrequencies were equal, as seen across spatial frequencies and at allgrade levels and as illustrated in FIGS. 2 to 5, when the child had atleast two practice thresholds. This test enabled screening normal fromdyslexic children with 100% accuracy, which was confirmed usingindependent measures from standardized dyslexia tests and teacher andstudent verbal reports. Only by mapping out the CSFs for testfrequencies surrounded by one of a four-octave range of backgroundfrequencies, centered about the test frequency, are these uniquelydifferent direction discrimination CSFs found for normal and dyslexicchildren. The absolute difference in DD-CSFs and the different patternsin DD-CSFs enable rapid and reliable diagnosis of dyslexia, that is,reading difficulty in children who are otherwise normal, in childrenover 5 years of age.

The Dyslexia Screener (TDS) was used to assess a child's readingability, since it can be administered in less than 5 minutes and showshigh validity (over 85%) for classifying dyslexic children into one ofthree categories: dyseidetic (spelling problems), dysphonetic(pronunciation problems), and mixed. However, the TDS cannot beadministered until the child is in the second grade, as it relies on thechild's ability to decode words (identify by naming) and encode words(spell eidetically and phonetically). The TDS also measures the child'sreading grade level.

During this study we discovered that normal and dyslexic readersdisplayed a different pattern of results, with these differencesenabling dyslexic children in first grade to be identified after twopractice thresholds. By the end of the first grade, this diagnosis wasconfirmed using the TDS. Based on the TDS and the directiondiscrimination CSFs, children were divided into two groups at the end ofthis study: those who had normal visual function and those who haddyslexia The TDS revealed that the 10 dyslexic children in grades 2 and3 fell into approximately equal proportions into each of the threesubtypes, consisting of four dyseidetic, two dysphonetic, and fourmixed. As there were no significant differences between the CSFs ofthese three subtypes of dyslexia, the data from all dyslexic children ateach grade level were grouped together.

Exemplary test window 134 was configured as a fish, and the computer 102was configured to present a "fish game" to children in which therepeated asking of whether the fish moved to the right or to the leftwas carried out. Repetition of displaying the background and the testpattern at different contrasts and spatial frequencies to children(i.e., practicing the fish game) causes CSFs for directiondiscrimination to rise in all children, including those who readnormally and those with reading difficulty. Children of different agesrequire different amounts of practice.

The greatest improvements when discriminating between test frequenciesof 1 cpd and 2 cpd were obtained for a first-grade normal reader aftertwo practice thresholds, as shown in FIGS. 3f, 4f, and 11c, whereas thechild in the third grade shows the least amount of improvement for thesetest frequencies, as shown in FIGS. 3f, 4f, 7a, and 13b-e. Thisindicates that the child aged 6 to 7 years old is in a critical periodwhere the plasticity of the neural channels can be modified more easilyby visual experience than is found for the child who is 8 years old.Practice on each of 20 different combinations of test-pattern andbackground frequencies improved direction discrimination CSFs 3 to 4fold, as shown in FIG. 7b. Practice one time on each pattern wassignificant (p<0.0001) in improving the child's direction discriminationCSFs, providing rapid remediation. This can be seen by comparing theoriginal (orig.) and practiced, either following one practice threshold(1prac) or two practice thresholds (2prac) shown in FIGS. 2-5b, c, and dfor normal and dyslexic children at each test frequency and grade level.The earliest and largest improvements in a child's CSF occur when testand background frequencies are equal, suggesting that visual processingtakes place within single, visual cortical, spatial frequency channels(e.g., 0.5 cpd in the test and 0.5 cpd in the background), rather thanwithin combinations of different spatial frequency channels (e.g., 0.5cpd in the test and 2 cpd in the background, and improve the most withpractice.

This study found that remediation was most rapid when the child wassetting up the neural networks that enable text to be decoded andencoded, and at around 6 to 7 years old. The largest improvements in achild's CSF occurred when test and background frequencies were equal, asshown in FIGS. 2-5b,c, and d, suggesting that changes within a singlespatial frequency channel improved the most with practice, rather thanwithin combinations of different spatial frequency channels.

The CSFs for a normal first and second grader who completed two or morepractice thresholds (2prac) equaled the normal adult's CSF when test andbackground frequencies were equal, as shown in FIGS. 2f, 3f, 4f, 8c, 9dand e, 11c, and 12c. On the other hand, as the test frequency increasedfrom 0.5 cpd to 2 cpd, a child in grade 3, both normal and dyslexic,showed the least amount of improvement after two practice thresholds, asshown in FIGS. 2f, 3f, 4f, and 13a. Moreover, the highest averageincrease in a normal child's CSF following one practice threshold wasfound for children in the second grade as shown in FIG. 7b, improvingfrom 3 to 8 fold with an average of 5 fold across frequencies, whereasnormal first graders improved an average of 4 fold and third graders anaverage of 3 fold across spatial frequencies. Therefore, remediation wasmost rapid for the 6- to 7-year-old child.

The rapid increase in the child's CSF with only 2 practice thresholds infirst grade, and the over two fold lower CSFs for practiced normalobservers in third grade indicates that the ability to discriminateleft-right movement is in a critical period when the child is 6 to 7years old, enabling rapid remediation with only two practice thresholds.This can be seen more clearly by examining the individual data in FIGS.8 to 13, where the CSFs on individual sessions are plotted. Theindividual graphs of a large subset of both dyslexic and age-matchednormals following practice at each grade level for test frequencies of0.5 cpd and 1 cpd are plotted in FIGS. 8a to 13a.

When the test frequency was 0.5 cpd as shown in FIGS. 2a-e, 8a-d, 9a-g,and 10a-e, then:

(1) following one practice threshold (shown in FIG. 2e), there was aprogressive increase in the child's direction discrimination CSFs as thechild advanced from grade 1 to grade 3;

(2) following two practice thresholds (shown in FIGS. 2f, 8b-d, 9c-g,and 10b-e), normal children in grades 1 to 3 always had the highest CSF,whereas dyslexic children had the lowest CSF, when test and backgroundfrequencies were equal, i.e., the CSFs for dyslexic and normalage-matched children were tightly coupled into two different groups; and

(3) the largest improvement in direction discrimination CSFs followingpractice, from 3 to 8 fold, occurred for both normal and dyslexicchildren at all grade levels (shown in FIGS. 7a and b).

This improvement in the CSF following practice decreased as the testspatial frequency was increased, as shown in FIGS. 7a and b. Theseresults indicate that 0.5-cpd test frequencies activate the mechanismused for left-right movement discrimination in the center of its workingrange. Moreover, students reported that they found the task easiest whendiscriminating left-right movement of 0.5-cpd and 1-cpd test patterns.

The individual graphs when discriminating the direction 1-cpd testgratings moved are presented in FIGS. 11 to 13. It can be seen that bothdyslexic and normal third graders showed less improvement overall (shownin FIGS. 13a-e) when discriminating left-right movement of 1-cpd testgratings, as opposed to a 0.5-cpd test pattern (shown in FIGS. 10a-e).The smaller effects of remediation at 1 cpd across grade levels is shownin FIG. 7a. Moreover, both dyslexic (shown in FIGS. 11b and d) andnormal (shown in FIG. 11c and d) first graders have much higher CSFsfollowing two practice thresholds than do third graders (shown in FIG.3f). The CSFs of 7-year-old students following two practice thresholds(shown in FIGS. 3f and 12b-d) are lower than the CSFs of 6 year olds andhigher than the CSFs of 8 year olds. These data provide more supportthat remediation is most rapid when the child is 6 to 7 years old,demonstrating that the neural channels are more able to be modified byvisual experience at 6 to 7 years old.

At high test frequencies of 2 cpd, all children reported that the taskwas more difficult, because of the small lateral movement of the testpattern (about 5 pixels to the left or right relative to the backgroundpattern). The children all reported that they found this task easiestwhen fixating on the round "nose" of the fish to discriminate left-rightmovement It was at this high test frequency that the largest differencesbetween normal and dyslexic children (shown in FIG. 7c) were found atall grade levels and frequency combinations (shown in FIG. 4). However,the smallest improvements following one practice threshold on eachfrequency combination were found when the test frequency was 2 cpd(shown in FIGS. 7a and b).

Discriminating the direction that a 0.25-cpd test frequency moved wasperceived to be a different task by many students. Oscillation of thetest frequency, instead of moving in a single direction was seen,especially when medium and high contrasts were needed to discriminateleft-right movement. In addition, a different pattern of results wasobtained, with the CSF being highest when the background was one octavelower than the test frequency, and lowest when the background was oneoctave higher than the test frequency. This pattern shows that maximummasking occurs at two times the value of the test frequency, at thesecond harmonic frequency, indicating nonlinear processing that couldresult from pooling across several different neural channels. This isparticularly evident when examining FIG. 5d, showing the CSFs for 8 yearolds when the test frequency equaled 0.25 cpd. Moreover, at this lowtest frequency, the differences between normal and dyslexic observerswere not consistent across grade level, having the smallest differencesbetween normal and dyslexic third graders, and the largest differencesbetween normal and dyslexic first graders (shown in FIG. 7c).Furthermore, the CSF of the practiced 7-year-old child showed the mostimprovement (shown in FIG. 5f), suggesting that direction selectivityusing this test frequency matures later than direction discriminationusing higher test frequencies.

With only forty minutes of entertaining visual exercise, 5 to 10minutes/week, rapid and effective remediation was provided when judgedrelative to a wide range of background frequencies. This study providessubstantial evidence that practice discriminating left-right movement,especially at 6 to 7 years old, provides rapid remediation, most likelyby developing networks in magnocellular streams. In addition, 10 to 40minutes of entertaining visual exercise tunes up the networks inmagnocellular (movement) streams so that direction discrimination CSFsimprove 3 to 4 fold.

When asked in a questionnaire at the end of this study if the childnoticed any difference in their reading ability following practice, allchildren said that reading out loud or silently was much easier, seeingthe individual letters in the middle of a word was easier, spelling, andpronunciation were easier, as were reading comprehension, speeddiscrimination, motion parallax, seeing moving objects at a fartherdistance, and distance judgments. All children were grateful for thetesting. They found the test entertaining and that they enjoyed readinga lot more and that they read a lot more, usually twice as much,immediately following the testing where the child practiceddiscriminating left-right movement. More practice gives more improvementin reading rates in all children, and major improvement can be obtainedfor just 5 to 10 minutes/week of play for 8 weeks.

The more a child practiced discriminating left-right movement, the morethe child's reading rates increased, increasing up to 14 fold for onedyslexic second grader (m1) who had three practice thresholds on eachpattern combination. With only two practice thresholds (shown in FIGS.2f to 5f and FIGS. 8f to 13), a normal 6- to 7-year old child's CSF forequal test and background frequencies equaled the CSF of a normal adult.Moreover, remediation was most rapid when the direction of movement wasjudged relative to low background frequencies, providing a wide frame ofreference for left-right movement discrimination, thereby facilitatingmovement discrimination.

The methodology of the present invention may be implemented in softwareand method for determining the lowest or "threshold" contrast requiredby a subject to discriminate the direction of motion, left versus right,of a vertical sine-wave grating of one spatial frequency (0.25, 0.50,1.0, or 2.0 cycles per degree of visual field) in a small test window ona background containing a vertical sine-wave grating of a spatialfrequency 1/4, 1/2, 1, 2, and 4 times the test spatial frequency. Thethresholds are determined objectively and rapidly by use of atwo-alternative-forced-choice psychophysical method that is embedded inthe fish game.

Contrast sensitivity is the reciprocal of contrast threshold. Thecontrast sensitivity function (CSF) for each test-pattern spatialfrequency is the family of contrast sensitivities for that test-patternspatial frequency over all of the predetermined background frequencies.Normal adult readers have high contrast sensitivities; moreover, thepattern of their CSFs show highest contrast sensitivity when the spatialfrequency in the test window is matched by the spatial frequency in thebackground. Normal children without reading difficulty have somewhatlower CSFs but the normal pattern. Dyslexic subjects, both children andadults, have substantially lower CSFs and an inverted pattern in theCSFs; that is, their CSFs show lowest contrast sensitivity when thespatial frequency in the test window is matched by the spatial frequencyin the background. Practice on the fish game causes directiondiscrimination CSFs to rise in all children and dyslexic adults, thoughdyslexic subjects start at a lower contrast sensitivity than normalreaders. Practice on the fish game also causes the dyslexic patternobserved in CSFs to invert to the normal pattern. Along with thesechanges in CSFs, reading rates increase several fold in normal readersand even more in dyslexic subjects.

Unfiltered words of a sans-serif font, such as Lucida Sans TypewriterBold, were used to create text that was centered on the display. Asans-serif font with rounded edges was chosen because this is the leastornate font, with no jagged or protruding edges, thereby being one ofthe easiest to read. Sample unfiltered text is shown in FIG. 1c. Whitetext on a black background having 100% contrast was used for unfilteredtext, since this text was easier for children to read than black text ona white background. Each letter in the text was 0.5 cm wide and 0.5 to0.75 cm high, depending on whether upper or lowercase letters weredisplayed This size letter enabled text to be read easily at a distanceof 57 cm from the screen. Reading materials were adapted from easy tounderstand text with a positive connotation, i.e., Over In The Meadow,by Jack Ezra Keats. This text was chosen, since it is taught to firstgraders at the elementary school used for testing. Therefore, thereading level of the text did not limit the child's reading performance.At the beginning of this study, the text had not been memorized by anyof the children in this study. To ensure that the text could not bememorized, the text was extended from 80 sentences in the original textto 230 five word sentences, so that text that never repeated was used tomeasure reading rates for filtered and unfiltered text. Reading rates atthe end of the study were measured using only the novel text, so thatmemorization could not contribute to measuring faster reading rates.Subsequent portions of the same text were used to test reading rates forboth filtered and unfiltered words, so that the reading of sentences inthe text was continuous, yet never repetitive. Therefore, text of equaldifficulty was used throughout the reading rate task to measuregrayscale and colored text that was either filtered or unfiltered. Sincemost of the text was novel, being written by the author, in conjunctionwith the school's reading specialist and a 6-year-old child, unfamiliarreading materials were used, for the most part to measure reading rates.

Words were first magnified and then filtered, since reading performanceis based on retinal based angular frequencies, and not object-basedspatial frequencies. Words were filtered as a unit, and the filteredwords, having a border equal to one letter width, were strung togetherin texts. There were often borders between the filtered word images, dueto the scaling mentioned above. All children reported, however, thatthese borders were blurred and did not help segment the text string intowords. The space between each word was the more salient cue that wasused to segment the text string.

Samples of filtered text for several children in this study are shown inFIG. 1c. The individualized filters, causing white on black text to bedisplayed in shades of gray, are matched to each observer's CSF, tocompensate for these CSF losses. Note that filtered text for eachobserver has different amounts of enhancement across the range ofspatial frequencies tested, seen as differences in the amount and extentof dark ringing around each letter. The transfer function of the filterwas designed to enhance images that have been degraded by noisydetectors when the degrading optical transfer function, like theNormalized CSF (NCSF), discussed below, as used in this study, is known.The detailed methods used to construct these filters have been describedpreviously and are also presented below.

The number of words per minute was increased on each step by increasingthe distance in pixels that the image moves between frames. Eachsentence, flanked by four letters of adjacent text at the beginning andend, was scrolled from right to left at different speeds. The number ofpixels the image moved before beginning each frame was adjusted so thatthe image moved over to the right a larger number of pixels at higherreading rates. The step size for increasing reading rates increasedgradually using a 12 words/min step size at low reading rates, and up toa 30 words/min step size at high reading rates. The reading speeds weremeasured with a digital stopwatch. The updating of the text images(scrolling) occurred at regular intervals, enabling Xwindow primitivesto generate smooth scrolling of text at all speeds.

Reading rates, defined as the fastest speed that can be used to readfiltered or unfiltered text scrolled across the screen, were measuredafter the CSFs were determined. Reading rates were only measured forchildren in grades 1 to 3. Filtered or unfiltered text was displayed atincreasing speeds, from 10 words/minute up to 700 words/minute, untilthe child could no longer correctly identify the text. Reading rateswere measured after one complete sentence had been presented to thechild who read the sentence out loud, either during or after thesentence was displayed. The next sentence was displayed as soon as thechild finished reading the sentence. Following the first incorrectresponse, a forced-choice double-staircase procedure, determining thespeed for 79% correct responses, was used to determine reading ratethresholds by increasing or decreasing the speed used to scroll eachsentence across the screen. The child had to correctly identify eachsubsequent sentence in the text being scrolled across the screen threetimes in a row at the same speed, before the reading speed was increasedone step. The reading speed was decreased one step each time thesentence was identified incorrectly. The sentence was scored asidentified correctly if 4 of 5 words were correct and in the rightorder.

Filtered text was presented before unfiltered text to counterbalance anyeffects of practice that might be attributed to the improved readingrates found when reading filtered text. Since reading rates alwaysincreased over the session, fatigue did not contribute to the slowerreading rates obtained for unfiltered text. Unfiltered and filteredtexts were cycled through in the same order throughout the session sothat practice effects were distributed equally across filtered andunfiltered text. One to two thresholds for each type of text, dependingon the difficulty the observer had reading, were used to determine themean reading rate threshold.

A child's ability to read is developing as the child advanced in agefrom 6 to 8 years old. We found that the mean reading rates forunfiltered text were significantly faster (p<0.0001) as the normal childadvanced from first to third grade, when analyzed using a test forpaired comparisons. This was found at the beginning of this study (shownin FIG. 14a), following practice (shown in FIG. 14b), and followingpractice at the low mean luminance, e.g., 8 cd/m² (shown in FIG. 14c),used to evaluate the effects of colored filters on reading rates.

Filtered text was always read at least 2 fold faster, on average, thanunfiltered text, as illustrated in FIGS. 15a-d. By compensating for CSFlosses to discriminate between brief orthogonally oriented sine-wavegratings, filtered text enabled the child to read significantly faster(p<0.0001). All children reported that the filtered text improved theirability to see individual letters in each word. Filtered text improvedreading rates about 3 fold for 6 to 7 year olds and 2 fold for 8 yearolds before practice, and about 2 fold after practice, as shown FIGS.14a-c.

As the child's sensitivity more closely approached the CSF of an adult,the less the filtered text proportionately improved reading rates.Filtered text can be used not only to improve reading performance, butalso to provide a second type of text to test the relative improvementin a child's reading ability following various types of remediation. Inaddition, finding that reading rates increased from 3 to 14 fold, whenCSF losses were compensated for by these image enhancement filters andthe child practiced discriminating left-right movement, shows thatchildren's CSFs to discriminate between orthogonally orientated briefpatterns and discriminate the direction of movement are closely relatedto their reading performance.

Practice on each of 20 different test-background frequency combinationsimproved reading rates from 2 to 9 fold on the average (shown in FIG.15a). Since a difference of 20 words per minute for slow readers cancorrespond to a doubling in their reading rates, whereas this differencefor fast readers would not be significant, each student's mean readingrate for filtered text was divided by the mean reading rate forunfiltered text, normalizing the proportion the student improved whenreading filtered text. Only in this manner can proportionateimprovements in reading rates for different students, between filteredand unfiltered text before and after practice, be compared and pooled toprovide summary curves, as shown in FIGS. 15a-d. All proportionateincreases greater than 1.0 show that reading rates were faster forfiltered text than for unfiltered text. One second-grade child withreading problems improved up to 14 fold after practicing 3 to 5 times oneach of the 20 different test pattern/background combinations.

Following practice discriminating left-right movement, reading rates forfiltered text approximately doubled again from the reading rates forfiltered text measured initially. Therefore, instead of measuring a 2-to 3-fold improvement in reading rates for filtered text (shown in FIG.15b), a 3- to 9-fold average improvement in filtered reading ratesfollowing practice was measured (shown in FIG. 15c). Moreover, followingtwo practice thresholds, a 9-fold improvement in reading rates whenreading filtered text, with a 4-fold improvement when reading unfilteredtext, was found for the normal first-grade child (shown in FIG. 15b),both the normal and dyslexic second-grade child (shown in FIG. 15c), andthe dyslexic third-grade child (FIG. 15d). Thus, filtered text forremediation is most effective when the child is 6 to 7 years old, whichcoincides with the development of the neural channels used for reading.

Filtered text can be used not only to improve reading performance, butalso to provide a second type of text to test the relative improvementin a child's reading ability following various types of remediation. Inaddition, finding that reading rates increased from 3 to 14 fold, whenCSF losses were compensated for by these image enhancement filters andthe child practiced discriminating left-right movement, shows thatchildren's CSFs to discriminate between orthogonally orientated briefpatterns and discriminate the direction of movement are closely relatedto their reading performance.

This example shows that spatial filtering is a powerful tool forimproving the reading performance of ARMD observers. The transferfunction of the filter is designed to enhance images that have beendegraded by noisy detectors, when the degrading optical transferfunction, like the NCSF as used in this study, is known It is alsoimportant to adjust the filter design parameters (see below) so thatreading rates are optimized, and to ensure that the angular pixelspacing is sufficiently small. This filtering approach replaces inadvance, at the front end, the contrast that is selectively reduced bythe child's developing visual system. By boosting the less visiblespatial frequency components, we are making pattern components in thespatial frequency band that is used for reading easier to see. Thecombination of text prefiltering and reduced visual function presumablypresents to that child's brain letters having spatial frequencycomponents with the same relative amplitudes as those seen by a normaladult observer. In other words, precompensation filtering for a knowndegradation is used to improve a child's reading performance. Inaddition, the filtered text provided a second independent measure usedto evaluate improvements in a child's reading performance followingpractice.

These image enhancement filters are unique and work well to improve thereading performance of observers with CSF losses compared to a normaladult, because (1) the use of the observer's NCSF to quantify their CSFlosses in the design of the filtering transfer function H(f), (2) theuse of the form of H(f) in Equation (3) below which has been shown to beeffective in deblurring of noisy images when compared to simplerfiltering functions such as 1/NCSF or 1/(NCSF+constant), (3) thefiltering parameter, MaxGain, is adjusted so that it is optimized forthe display screen's pixel density, and (4) the observer's viewingdistance is adjusted so that static text is read most easily at thisdistance. Only when text is enhanced using the individualized NCSF-basedfilters described in this study does filtered text significantly reducethe magnification required for reading and increase reading rates inobservers with CSF losses.

Although the mean reading rates for all dyslexic and normal children inthis study increased significantly (p<0.0000000001 [E-19]) as the childadvanced from first to third grade, as shown in FIGS. 14a-c, the average30% reduction in reading speed that was found when reading colored texthaving the same contrast and mean luminance, 8 cd/m2, as grayscale textwas quite constant across: (1) colors, i.e., green, red, blue, andyellow text, (2) type of text, filtered or unfiltered, as shown in FIG.1b, and (3) type of observer, dyslexic or normal in grades 1 to 3, withcolored text being read significantly more slowly (p<0.0000000001) thangrayscale text. In fact, the reading rates for equiluminant text havingonly color contrast, tested on a subset of these students, were readeven 30% slower, on the average, than colored text have both luminanceand color contrast. This same pattern of results was found for adultsalso. Therefore, when parvocellular networks were activated more thanmagnocellular networks by presenting colored text, then reading rateswere always reduced.

Grayscale clipping of the displayed stimulus was avoided by scaling theminimum pattern intensity to the lowest display intensity and themaximum pattern intensity to the highest display intensity, using linearinterpolation. The resealing does not change the relative contrast ofthe Fourier components in the image, since both linear interpolation andFourier analysis are linear operations. It does, however, modify themean luminance level of text and background, compressing the contrastrange of the filtered text (shown in FIG. 1c). The background goes fromblack to gray to make room for the dark outline the filter places aroundeach letter. The filtered text was stored off-line to be used in thenext session for testing the observer's reading rates.

The transfer function chosen for the image-enhancement filter inaccordance with the invention is:

    H(f) NCSF(f)÷[NCSF.sup.2 (f)+(2MaxGain).sup.-2 ]       (1)

where f is the radial spatial frequency expressed in cyc/deg by:

    f=sqrt(u.sup.2 +v.sup.2)                                   (2)

where u and v are horizontal and vertical spatial frequency,respectively, and NCSF(f) is defined to be:

    NCSF(f)=Child's CSF(f)÷Normal Adult's CSF(f)           (3)

The transfer function is designed to enhance noisy images that have beendegraded by a known optical transfer function. The maximum amount ofenhancement in the spatial frequency domain using this transfer functionis set by the factor MaxGain. It is important that the MaxGain valuethat maximizes reading rates be determined for the display being used topresent filtered text. Otherwise, the filtered text will not improvereading rates over unfiltered text. Thus, empirically we discovered thatthe optimal value for MaxGain is dependent on the display's pixeldensity, such that a higher MaxGain, i.e. more enhancement, is neededwhen the screen has a lower pixel density. MaxGain was set to 4.5 forthis study, since this value was optimal for all observers tested.Moreover, it is important that the transfer function be anchored at zerospatial frequency to no enhancement to ensure that the same range ofcontrasts are being compared when reading filtered and unfiltered text.

The pixel density on the display screen was measured as 40 pixels percentimeter, implying a pixel spacing of Δx=0.025 cm. The angular pixelspacing at the observer's eye, using the small angle approximation, is:

    arctan [Δx/d]≈Δx/d                     (4)

in radians, where d is the viewing distance in cm, or:

    Δθ=(Δx/d)(180/π)=4.5/πd            (5)

in degrees. The constant 180/π converts from radians to degrees. This is0.025 degrees at a 57 cm viewing distance. We used the Discrete FourierTransform (DFT), and the Nyquist (folding) frequency is:

    f.sub.N =1/(2Δθ)=πd/9                       (6)

in cycles per degree (cyc/deg). This is 19.9 cyc/deg at a 57 cm viewingdistance.

For each subject, we composed a 15-by-15 element two-dimensionaltransfer function by spreading the H(f) values for that subject radiallyfrom f=0 at the origin of frequency space up to f=sqrt(F_(N)) at the endof each axis. In the transfer function, horizontal frequency, u, andvertical frequency, v, varied between -sqrt(F_(N)) and sqrt(F_(N)) in 15equal steps. This range of spatial frequencies enabled filteringfrequency components from 0.8 up to 4.5 cyc/deg. This frequency scalingusing sqrt(F_(N)) to delimit the upper frequency cutoff, instead off_(N), shifting the range of spatial frequencies being filtered to 3fold lower spatial frequencies, was shown to improve reading rates byapproximately 20% when compared to filtering up to the Nyquistfrequency, f_(N). Moreover, data in our laboratory subsequent to thisstudy, on five second-grade students, both normal and dyslexic, foundthe same 20% improvement in reading rates when using sqrt(F_(N)) todelimit the upper frequency cutoff, instead of f_(N). Since only spatialfrequencies spanning 3 cycles/letter are used for letter recognition,then for letters 0.5 cm wide that are seen at a viewing distance of 57cm, only spatial frequencies up to 6 cyc/deg are used for letterrecognition. Each enhancement filter was designed not only for aspecific subject, but for a specific viewing distance as well, since theNyquist frequency [Eq. (6)] is distance dependent The inverse DFT wasused to compute a 15-by-15 convolution kernel to be used forenhancement.

Since the transfer function was generated to be circularly symmetricabout zero frequency, the computed convolution kernel was circularlysymmetric about the origin as well. Also, since each observer's CSF wasexpressed in angular frequency, differences in viewing distance wereaccounted for intrinsically. Words were filtered in the spatial domainby the process of convolution, that is, by summing the products of the15-by-15 coefficient weights of the convolution kernel times the graylevel of each center pixel and its surrounding 224 pixels. The filteredpixel intensity=Sum (15×15 spatial filter ^(*) unfiltered pixel value).The elements of the spatial filter kernel matrix, computed by the DFT,were ordered to be symmetrical about the center of the filter. Thelargest weights were in the center of the filter.

The uniqueness of the approaches exemplified above to investigate visionand reading is based on five different lines of evidence. First, thisstudy found a different pattern of results between normal and dyslexicchildren, both before and after practice, when discriminating thedirection of moving patterns, enabling rapid and reliable screening fordyslexia in 5 minutes for children in grades 1 to 3. This differentpattern of results shows the importance of evaluating inhibitorynetworks for rapid dyslexia screening. Only by mapping out the CSFs fortest frequencies surrounded by one of a 4 octave range of backgroundfrequencies, centered about the test frequency, were these uniquelydifferent direction discrimination CSFs found for normal and dyslexicchildren. Moreover, only by judging movement relative to backgroundfrequencies equal to or higher than the test frequency, were theintegrity of inhibitory networks able to be uncovered. Second, 10 to 40minutes of entertaining visual exercise tunes up the inhibitory networksin magnocellular (movement) streams so that both directiondiscrimination CSFs improved 3 to 4 fold, and reading rates improved 3to 14 fold, in addition to markedly noticeable improvements, at least adoubling, in reading comprehension, spelling, pronunciation, as well asmovement and depth discrimination. Third, when vertically orientedsine-wave gratings were presented to measure direction discriminationthresholds, enabling the output of simple cells to mediatediscrimination, then 9-fold larger differences between normal anddyslexic children were measured, than found previously using random dotpatterns, showing that vertical sine-wave gratings are the optimalstimulus for rapid and reliable screening. Fourth, measuring readingrates to continuous, non-repetitive, easy-to-read, scrolled text,provides an objective measure of reading performance that can be madebefore and after practice discriminating left-right movement to evaluateimprovements in reading, instead of measuring reading performance byrelying on subjective teacher evaluations, as is currently done. Inaddition, definitive evidence that magnocellular, and not parvocellularnetworks, play a major role in reading was obtained by comparing readingrates for grayscale and colored text equated in luminance and contrast.Fifth, individualized filtered text that compensates for losses in achild's CSF to discriminate between orthogonally oriented briefpatterns, compared to a normal adult, improved reading rates from 2 to 4fold, providing more evidence that magnocellular networks play a majorrole in reading, and that they are still developing in all children 5 to9 years old. This filtered text not only can be used for remediation,but also can be used to provide a second independent measure of readingrates, when compared to high contrast unfiltered text, to objectivelyevaluate improvements in reading performance. This unique approachprovides conclusive evidence that magnocellular and inhibitory networksin the brain play a major role in reading, both in directing eyemovements and in word recognition.

Those skilled in the art will understand that the preceding exemplaryembodiments of the present invention provide the foundation for numerousalternatives and modifications thereto. These other modifications arealso within the scope of the present invention. Accordingly, the presentinvention is not limited to that precisely as shown and described above.

What is claimed is:
 1. A method for diagnosing dyslexia by measuringcontrast sensitivity for motion discrimination of a subject having avisual cortical movement system, said method comprising the steps of:(a)displaying a background with a contrast and a spatial frequency; (b)displaying a test window within said background, said test windowincluding a test pattern with a contrast and a spatial frequency, saidtest pattern replacing said background;said contrasts being within arange which stimulates the visual cortical movement system of thesubject; said spatial frequencies being within a range which stimulatesthe visual cortical movement system of the subject; (c) moving said testpattern within said test window in either a first direction or a seconddirection; (d) receiving a signal from the subject indicative of eithersaid first direction or said second direction; (e) modifying at leastone of said contrasts or said spatial frequencies in response to saidsignal; (f) repeating steps (a) through (e); and (g) using the signalsfrom the subject as criteria for forming a diagnosis of dyslexia.
 2. Amethod as claimed in claim 1 wherein said step of displaying a testwindow comprises the step of:displaying said test pattern with a spatialfrequency selected from a predetermined range of spatial frequencies;said predetermined range of spatial frequencies of said test patternincluding spatial frequencies ranging from about 0.25 cycle per degreeto about 2 cycles per degree.
 3. A method as claimed in claim 2 whereinsaid step of displaying a background comprises the step of:displayingsaid background with a spatial frequency selected from a predeterminedrange of spatial frequencies; said predetermined range of spatialfrequencies of said background including spatial frequencies that are1/4, 1/2, 1, 2, and 4 times said spatial frequency at which said testpattern is displayed.
 4. A method as claimed in claim 3 wherein saidmodifying step comprises the steps of:increasing said contrast of saidtest pattern if said signal is incorrect; and decreasing said contrastof said test pattern if said signal is correct.
 5. A method as claimedin claim 4, wherein said step of modifying further comprises the stepsof:varying said spatial frequency at which said background is displayedwhile maintaining constant said spatial frequency at which said testpattern is displayed.
 6. A method as claimed in claim 5, wherein saidstep of modifying further comprises the steps of:varying said spatialfrequency at which said test pattern is displayed after said spatialfrequency of said background is varied through each of said spatialfrequencies of said predetermined range of spatial frequencies.
 7. Themethod of claim 4, wherein the contrast of said test pattern isdecreased only when a sequential number of signals are correct.
 8. Themethod of claim 7, wherein the number is three.
 9. A method as claimedin claim 1 wherein:said step of displaying a background comprises thestep of displaying said background at a contrast selected from apredetermined range of contrasts; and said step of displaying a testwindow comprises the step of displaying said test pattern at a contrastselected from a predetermined range of contrasts; said predeterminedranges of contrasts including contrasts of less than about 10%.
 10. Amethod as claimed in claim 9, wherein said step of displaying abackground comprises the step of:displaying said background at acontrast of about 5%.
 11. A method as claimed in claim 1 wherein:saidstep of displaying a test window comprises the step of displaying saidtest pattern at an initial position within said test window for apredetermined period; and said step of moving comprises the step ofdisplaying said test pattern at a final position within said test windowfor a predetermined period.
 12. A method as claimed in claim 11,wherein:said step of displaying said test pattern at an initial positioncomprises the step of displaying said test pattern for less than about0.2 second; and said step of displaying said test pattern at a finalposition comprises the step of displaying said test pattern for lessthan about 0.2 second.
 13. A method as claimed in claim 11, wherein:saidstep of displaying a background comprises the step of displaying saidbackground as substantially vertical stripes which alternatesinusoidally between light and dark at said spatial frequency; and saidstep of displaying a test window comprises the step of displaying saidtest pattern as substantially vertical stripes which alternatesinusoidally between light and dark at said spatial frequency.
 14. Amethod as claimed in claim 8 wherein said step of moving comprises thestep of displaying said test pattern at said final position, said secondposition being either to the right or to the left of said firstposition;said predetermined periods at which said test pattern isdisplayed at said initial and final positions being of a duration toinduce in the subject an apparent sense of motion of said stripes movingright or left from said initial position to said final position.
 15. Amethod as claimed in claim 1 wherein said method diagnoses dyslexia bymeasuring an absolute value of the contrast sensitivity for motiondiscrimination.
 16. A method as claimed in claim 15, further comprisingthe steps of:storing data based on said signals received from thesubject; and determining the contrast sensitivity based on said data.17. A method as claimed in claim 1 wherein said method diagnosesdyslexia by measuring contrast sensitivity for motion discrimination toyield a contrast sensitivity function with a shape.
 18. A method asclaimed in claim 1 wherein said method further improves the contrastsensitivity function for motion discrimination of the subject.
 19. Amethod as claimed in claim 1 wherein said method further improvesreading rate of the subject by improving the contrast sensitivity formotion discrimination.
 20. Apparatus for improving contrast sensitivityfor movement discrimination of a subject having a visual corticalmovement system, said apparatus comprising:a monitor; and a computerconnected to said monitor, said computer being configured to:(a) displaya background with a contrast and a spatial frequency; (b) display a testwindow within said background, said test window including a test patternwith a contrast and a spatial frequency said test pattern replacing saidbackground;said contrasts being within a range which stimulates thevisual cortical movement system of the subject; said spatial frequenciesbeing within a range which stimulates the visual cortical movementsystem of the subject; (c) move said test pattern within said testwindow in either a first direction or a second direction; (d) receive asignal from the subject indicative of either said first direction orsaid second direction; (e) modify at least one of said contrasts or saidspatial frequencies in response to said signal; and (f) repeat steps (a)through (e) a plurality of times.
 21. The apparatus of claim 20,operated to improve contrast sensitivity for movement discrimination ofa subject having a visual cortical movement system.
 22. The apparatus ofclaim 20 operated to improve the reading rare of a subject having avisual cortical movement system.
 23. Apparatus as claimed in claim 20,wherein said computer is further configured to display said test patternwith a spatial frequency selected from a predetermined range of spatialfrequencies;said predetermined range of spatial frequencies of said testpattern including spatial frequencies ranging from about 0.25 cycle perdegree to about 2 cycles per degree.
 24. Apparatus as claimed in claim23, wherein said computer is configured to display said background witha spatial frequency selected from a predetermined range of spatialfrequencies;said predetermined range of spatial frequencies of saidbackground including spatial frequencies that are 1/4, 1/2, 1, 2, and 4times said spatial frequency at which said test pattern is displayed.25. Apparatus as claimed in claim 20, wherein said computer isconfigured to:display said background at a contrast selected from apredetermined range of contrasts; and display said test pattern at acontrast selected from a predetermined range of contrasts; saidpredetermined ranges of contrasts including contrasts of less than about10%.
 26. Apparatus as claimed in claim 25, wherein said computer isconfigured to display said background at a contrast of about 5%. 27.Apparatus as claimed in claim 20, wherein said computer is configuredto:display said test pattern at an initial position within said testwindow for a predetermined period; and display said test pattern at afinal position within said test window for a predetermined period. 28.Apparatus as claimed in claim 27, wherein said computer is configured todisplay said test pattern at both of said positions for less than about0.2 second.
 29. Apparatus as claimed in claim 20, wherein said computeris configured to vary said contrast at which said test pattern isdisplayed.
 30. Apparatus as claimed in claim 29, wherein said computeris configured to vary said spatial frequency at which said background isdisplayed.
 31. Apparatus as claimed in claim 30, wherein said computeris configured to vary said spatial frequency at which said test patternis displayed.
 32. Apparatus as claimed in claim 20, wherein saidcomputer is further configured to display a blank field on said monitorbefore displaying said background and after moving said test pattern.33. Apparatus as claimed in claim 20, wherein said test window issubstantially circular.
 34. Apparatus as claimed in claim 20, whereinsaid background is substantially larger than said test window. 35.Apparatus as claimed in claim 20, wherein said computer is configured todisplay said field such that said test is about 20% as large as saidbackground.
 36. The apparatus of claim 20, wherein the contrast of thetest pattern is increased if the signal is incorrect, and wherein thecontrast of the test pattern is decreased if the signal is correct. 37.The apparatus of claim 36, wherein the contrast of said test pattern isdecreased only when a sequential number of signals are correct.
 38. Theapparatus of claim 37, wherein the number is three.
 39. An article ofmanufacture comprising:storage medium readable by a computer; andplurality of instructions stored on said storage medium and includinginstructions for:(a) configuring the computer to display on a monitor abackground with a contrast and a spatial frequency; (b) configuring thecomputer to display on a monitor a test window within said background,said test window including a test pattern with a contrast and a spatialfrequency, said test pattern replacing said background pattern;saidcontrasts being within a range which stimulates the visual corticalmovement system of the subject; said spatial frequencies being within arange which stimulates the visual cortical movement system of thesubject; (d) configuring the computer to move said test pattern withinsaid test window in either a first direction or a second direction; (e)configuring the computer to receive, via an input device connected tothe computer, from a subject a signal indicative of either said firstdirection or said second direction; and (f) configuring the computer tomodify at least one of said contrasts or spatial frequencies in responseto said signal; and (g) configuring said computer to repeat steps (a)through (f).
 40. A method for improving contrast sensitivity for motiondiscrimination of a subject having a visual cortical movement system,said method comprising the steps of:(a) displaying a background with acontrast and a spatial frequency; (b) displaying a test window withinsaid background, said test window including a test pattern with acontrast and a spatial frequency, said test pattern replacing saidbackground;said contrasts being within a range which stimulates thevisual cortical movement system of the subject; said spatial frequenciesbeing within a range which stimulates the visual cortical movementsystem of the subject; (c) moving said test pattern within said testwindow in either a first direction or a second direction; (d) receivinga signal from the subject indicative of either said first direction orsaid second direction; (e) modifying at least one of said contrasts orsaid spatial frequencies in response to said signal; (f) repeating steps(a) through (e).
 41. A method as claimed in claim 40, wherein said stepof displaying a test window comprises the step of:displaying said testpattern with a spatial frequency selected from a predetermined range ofspatial frequencies; said predetermined range of spatial frequencies ofsaid test pattern including spatial frequencies ranging from about 0.25cycle per degree to about 2 cycles per degree.
 42. A method as claimedin claim 41, wherein said step of displaying a background comprises thestep of:displaying said background with a spatial frequency selectedfrom a predetermined range of spatial frequencies; said predeterminedrange of spatial frequencies of said background including spatialfrequencies that are 1/4, 1/2, 1, 2, and 4 times said spatial frequencyat which said test pattern is displayed.
 43. A method as claimed inclaim 42, wherein said modifying step comprises the steps of:increasingsaid contrast of said test pattern if said signal is incorrect; anddecreasing said contrast of said test pattern if said signal is correct.44. A method as claimed in claim 43, wherein said step of modifyingfurther comprises the steps of:varying said spatial frequency at whichsaid background is displayed while maintaining constant said spatialfrequency at which said test pattern is displayed.
 45. A method asclaimed in claim 44, wherein said step of modifying further comprisesthe steps of:varying said spatial frequency at which said test patternis displayed after said spatial frequency of said background is variedthrough each of said spatial frequencies of said predetermined range ofspatial frequencies.
 46. The method of claim 43, wherein the contrast ofsaid test pattern is decreased only when a sequential number of signalsare correct.
 47. The method of claim 46, wherein the number is three.48. The method of claim 47, wherein the contrast of said test pattern isdecreased only when a sequential number of signals are correct.
 49. Themethod of claim 48, wherein the number is three.
 50. A method as claimedin claim 40, wherein:said step of displaying a background comprises thestep of displaying said background at a contrast selected from apredetermined range of contrasts; and said step of displaying a testwindow comprises the step of displaying said test pattern at a contrastselected from a predetermined range of contrasts; said predeterminedranges of contrasts including contrasts of less than about 10%.
 51. Amethod as claimed in claim 50, wherein said step of displaying abackground comprises the step of:displaying said background at acontrast of about 5%.
 52. A method as claimed in claim 40, wherein:saidstep of displaying a test window comprises the step of displaying saidtest pattern at an initial position within said test window for apredetermined period; and said step of moving comprises the step ofdisplaying said test pattern at a final position within said test windowfor a predetermined period.
 53. A method as claimed in claim 52,wherein:said step of displaying a background comprises the step ofdisplaying said background as substantially vertical stripes whichalternate sinusoidally between light and dark at said spatial frequency;and said step of displaying a test window comprises the step ofdisplaying said test pattern as substantially vertical stripes whichalternate sinusoidally between light and dark at said spatial frequency.54. A method as claimed in claim 53, wherein said step of movingcomprises the step of displaying said test pattern at said finalposition, said second position being either to the right or to the leftof said first position;said predetermined periods at which said testpattern is displayed at said initial and final positions being of aduration to induce in the subject an apparent sense of motion of saidstripes moving right or left from said initial position to said finalposition.
 55. A method as claimed in claim 52, wherein:said step ofdisplaying said test pattern at an initial position comprises the stepof displaying said test pattern for less than about 0.2 second; and saidstep of displaying said test pattern at a final position comprises thestep of displaying said test pattern for less than about 0.2 second. 56.A method for improving reading speed of a subject having a visualcortical movement system, said method comprising the steps of:(a)displaying a background with a contrast and a spatial frequency; (b)displaying a test window within said background, said test windowincluding a test pattern with a contrast and a spatial frequency, saidtest pattern replacing said background;said contrasts being within arange which stimulates the visual cortical movement system of thesubject; said spatial frequencies being within a range which stimulatesthe visual cortical movement system of the subject; (c) moving said testpattern within said test window in either a first direction or a seconddirection; (d) receiving a signal from the subject indicative of eithersaid first direction or said second direction; (e) modifying at leastone of said contrasts or said spatial frequencies in response to saidsignal; and (f) repeating steps (a) through (e).
 57. A method as claimedin claim 56, wherein said step of displaying a test window comprises thestep of:displaying said test pattern with a spatial frequency selectedfrom a predetermined range of spatial frequencies; said predeterminedrange of spatial frequencies of said test pattern including spatialfrequencies ranging from about 0.25 cycle per degree to about 2 cyclesper degree.
 58. A method as claimed in claim 57, wherein said step ofdisplaying a background comprises the step of:displaying said backgroundwith a spatial frequency selected from a predetermined range of spatialfrequencies; said predetermined range of spatial frequencies of saidbackground including spatial frequencies that are 1/4, 1/2, 1, 2, and 4times said spatial frequency at which said test pattern is displayed.59. A method as claimed in claim 58, wherein said modifying stepcomprises the steps of:increasing said contrast of said test pattern ifsaid signal is incorrect; and decreasing said contrast of said testpattern if said signal is correct.
 60. A method as claimed in claim 59,wherein said step of modifying further comprises the steps of:varyingsaid spatial frequency at which said background is displayed whilemaintaining constant said spatial frequency at which said test patternis displayed.
 61. A method as claimed in claim 60, wherein said step ofmodifying further comprises the steps of:varying said spatial frequencyat which said test pattern is displayed after said spatial frequency ofsaid background is varied through each of said spatial frequencies ofsaid predetermined range of spatial frequencies.
 62. A method as claimedin claim 56, wherein:said step of displaying a background comprises thestep of displaying said background at a contrast selected from apredetermined range of contrasts; and said step of displaying a testwindow comprises the step of displaying said test pattern at a contrastselected from a predetermined range of contrasts; said predeterminedranges of contrasts including contrasts of less than about 10%.
 63. Amethod as claimed in claim 62, wherein said step of displaying abackground comprises the step of:displaying said background at acontrast of about 5%.
 64. A method as claimed in claim 56, wherein:saidstep of displaying a test window comprises the step of displaying saidtest pattern at an initial position within said test window for apredetermined period; and said step of moving comprises the step ofdisplaying said test pattern at a final position within said test windowfor a predetermined period.
 65. A method as claimed in claim 64,wherein:said step of displaying said test pattern at an initial positioncomprises the step of displaying said test pattern for less than about0.2 second; and said step of displaying said test pattern at a finalposition comprises the step of displaying said test pattern for lessthan about 0.2 second.
 66. A method as claimed in claim 64, wherein:saidstep of displaying a background comprises the step of displaying saidbackground as substantially vertical stripes which alternatesinusoidally between light and dark at said spatial frequency; and saidstep of displaying a test window comprises the step of displaying saidtest pattern as substantially vertical stripes which alternatesinusoidally between light and dark at said spatial frequency.
 67. Amethod as claimed in claim 66, wherein said step of moving comprises thestep of displaying said test pattern at said final position, said secondposition being either to the right or to the left of said firstposition;said predetermined periods at which said test pattern isdisplayed at said initial and final positions being of a duration toinduce in the subject an apparent sense of motion of said stripes movingright or left from said initial position to said final position. 68.Apparatus for diagnosing dyslexia by measuring contrast sensitivity formovement discrimination of a subject having a visual cortical movementsystem, said apparatus comprising:a monitor; and a computer connected tosaid monitor, said computer being configured to:(a) display a backgroundwith a contrast and a spatial frequency; (b) display a test windowwithin said background, said test window including a test pattern with acontrast and a spatial frequency, said test pattern replacing saidbackground;said contrasts being within a range which stimulates thevisual cortical movement system of the subject; said spatial frequenciesbeing within a range which stimulates the visual cortical movementsystem of the subject; (c) move said test pattern within said testwindow in either a first direction or a direction; (d) receive a signalfrom the subject indicative of either said first direction or saidsecond direction; (e) modify at least one of said contrasts and/or saidspatial frequencies in response to said signal; (f) repeat steps (a)through (e) a plurality of times; and (g) use the signals from thesubject as criteria for forming a diagnosis of dyslexia.
 69. Apparatusas claimed in claim 68, wherein said computer is further configured todisplay said test pattern with a spatial frequency selected from apredetermined range of spatial frequencies;said predetermined range ofspatial frequencies of said test pattern including spatial frequenciesranging from about 0.25 cycle per degree to about 2 cycles per degree.70. Apparatus as claimed in claim 69, wherein said computer isconfigured to display said background with a spatial frequency selectedfrom a predetermined range of spatial frequencies;said predeterminedrange of spatial frequencies of said background including spatialfrequencies that are 1/4, 1/2, 1, 2, and 4 times said spatial frequencyat which said test pattern is displayed.
 71. Apparatus as claimed inclaim 68, wherein said computer is configured to:display said backgroundat a contrast selected from a predetermined range of contrasts; anddisplay said test pattern at a contrast selected from a predeterminedrange of contrasts; said predetermined ranges of contrasts includingcontrasts of less than about 10%.
 72. Apparatus as claimed in claim 71,wherein said computer is configured to display said background at acontrast of about 5%.
 73. Apparatus as claimed in claim 68, wherein saidcomputer is configured to:display said test pattern at an initialposition within said test window for a predetermined period; and displaysaid test pattern at a final position within said test window for apredetermined period.
 74. Apparatus as claimed in claim 73, wherein saidcomputer is configured to display said test pattern at both saidpositions for less than about 0.2 second.
 75. Apparatus as claimed inclaim 68, wherein said computer is configured to vary said contrast atwhich said test pattern is displayed.
 76. Apparatus as claimed in claim75, wherein said computer is configured to vary said spatial frequencyat which said background is displayed.
 77. Apparatus as claimed in claim76, wherein said computer is configured to vary said spatial frequencyat which said test pattern is displayed.
 78. Apparatus as claimed inclaim 68, wherein said computer is further configured to display a blankfield on said monitor before displaying said background and after movingsaid test pattern.
 79. Apparatus as claimed in claim 68, wherein saidtest window is substantially circular.
 80. Apparatus as claimed in claim68, wherein said background is substantially larger than said testwindow.
 81. Apparatus as claimed in claim 68, wherein said computer isconfigured to display said field such that said test is about 20% aslarge as said background.
 82. Apparatus as claimed in claim 68 whereindyslexia is diagnosed by measuring an absolute value of the contrastsensitivity for motion discrimination.
 83. Apparatus as claimed in claim68, wherein dyslexia is diagnosed by measuring contrast sensitivity formotion discrimination to yield a contrast sensitivity function with ashape.
 84. The apparatus of claim 68 wherein the contrast of the testpattern is increased if the signal is incorrect, and wherein thecontrast of the test pattern is decreased if the signal is correct. 85.The apparatus of claim 84, wherein the contrast of said test pattern isdecreased only when a sequential number of signals are correct.
 86. Theapparatus of claim 85, wherein the number is three.